Cyborg Baby Spinach Could One Day Detect Chemical Weapons

"I like to think/(right now, please!)/of a cybernetic forest/filled with pines and electronics/ where deer stroll peacefully/past computers/as if they were flowers/with spinning blossoms," poet Richard Brautigan wrote in 1967. His heavily optimistic (or heavily satirical) take on cyborg plants was prescient. Now, half a century later, researchers are working on giving baby spinach bomb-detecting capabilities.

That’s right. Cyborg baby spinach. Last week, a team of MIT researchers published a paper in Nature Materials demonstrating what happened when they inserted carbon nanotubes into chloroplasts, the photosynthetic engines of plant cells. The tubes’ ability to sense the presence of different chemicals around the plants, researchers say, could revolutionize leafy greens as we know them.

Researchers showed that the carbon nanotubes—tiny cylinders of carbon a thousand times thinner than a human hair—could slip into the chloroplasts without damaging them, and then actually give the chloroplasts a 30% boost in their ability to capture solar energy. The scientists also found that the tubes could detect the presence of the pollutant nitric oxide when they shined infrared light on the chloroplasts. (If you shine light on chloroplasts with nanotubes, the microscopic blobs will fluoresce. But in the presence of nitric oxide, the chloroplasts’ fluorescence dims.)

Carbon nanotube-enabled chloroplasts fluorescent under light.

Now that researchers have a basic understanding of how the tubes work in plants, it’s only a matter of time before they start inserting nanomaterials with even more advanced sensor capabilities—like carbon nanotubes that can detect TNT and sarin gas, they say. "Plant nanobionics," a term coined by lead author Juan Pablo Giraldo and MIT chemical engineering professor Michael Strano, could leverage your average shrub into a sophisticated data collector in places where humans are afraid to go.

Different carbon nanotubes can detect different chemicals with this method, but the scientists are still figuring out which pairs work together. It’s also important to find out what happens to the carbon nanotubes after a plant dies, and whether a buildup could be toxic in the soil.

There's still a long way to go, but Giraldo hopes to build on this discovery by creating a host of technologies that help plants communicate with scientists. "We envision designing a standoff detection instrument, a remote sensing instrument that can allow us one day to measure the fluorescent signal from the nanotubes under field conditions," Giraldo said. "You can put a monitor plant in a city for pollutants, or [measure] pesticides in a crop field, or perhaps explosives in an airport."